In 1930, Alexander Calder visited Piet Mondrian's studio and suggested to the Dutch painter that it would be lovely if his abstract compositions moved (Mondrian did not agree). Following this meeting, Calder broke with his previously figurative work and began to attempt purely abstract compositions which would change over time. By 1932, he was making moving geometric constructions from wire and sheet metal. As he recalled a few years later:

“I had been working on things with a little motion, some with more motion. I had quite a number of things that went round and round, driven by a small electric motor — some with no motor — some with a crank.”

Around 1933, Marcel Duchamp paid a visit to Calder's studio and was taken by the machines, suggesting immediately a name for them — “mobiles” — whose double meaning in French is both a “thing that moves” as well as “motive.”

At the same time and independently, Italian designer Bruno Munari was developing his own moving models. As opposed to the underlying “motive” of Calder's Mobiles, Munari named his constructions Useless Machines. Around 1933, Munari began to make his machines as “cardboard painted in plain colors, and sometimes a glass bubble, while the whole thing was held together with the frailest of wooden rods and bits of thread.” In Design as Art, Munari wrote about the difference between the pure geometric abstraction of his Useless Machines and the natural figures of Calder's Mobiles.

“There is a harmonic relationship between all the parts which go to make up a useless machine . . . . Mobiles are by nature different. The inspiration seems to be drawn from the vegetable kingdom.”

Continuing, Munari describes that “the pieces of a useless machine all turn upon themselves and in respect to each other without touching” and therefore the total composition is solely determined by the unpredictable independent movement of its parts at one point in time. Meanwhile, Alexander Calder’s compositions mimic natural form with individual parts subordinate to a continuous whole. “One might say that Calder was the first sculptor of trees.”